Evaluation of Accuracy of One-Step Nucleic Acid Amplification (OSNA) in Diagnosis of Lymph Node Metastases of Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) is the most common malignant thyroid neoplasm; it originates from follicular cells of thyroid gland, and represents over 80% of thyroid tumors. The incidence of PTC has progressively been increasing in the last decades, doubling since the 1970s, due to the diffusion of screening ultrasound. Although PTCs are considered slow-growing tumors, the incidence of node metastases is high, ranging from 20% to 90%. The real impact of node metastases on prognosis is still a matter of debate: reports in literature demonstrate a reduction of disease-free survival but are divergent on overall survival. Diagnostic tools have poor accuracy for central lymph node compartment, which is the most frequent site of metastases.

The last guidelines suggest a prophylactic central lymph node compartment dissection (CLND) in patients with high-risk PTC; nevertheless, this indication meets resistance due to the higher incidence of postoperative complications, especially hypoparathyroidism and recurrent laryngeal nerve (RLN) palsy.

Recently, new molecular biologic techniques have spread widely, mainly in diagnosis of node metastases in breast carcinoma; these assays allow to quickly isolate, amplify and quantify mRNA encoding for proteins selectively present in neoplastic cells, as Cytokeratine-19 (CK-19). One Step Nucleic Acid Amplification (OSNA) is routinely used in diagnosis of node metastasis in sentinel lymph node (SNL) of patients affected from breast cancer. The aim of this study is to evaluate if application of OSNA to intraoperative diagnosis of node metastases of PTC is possible.